This is a proposal to study the relation between number of siblings and the personal and social adjustment of adults. The research will be based on a national survey of 2,264 respondents age 21 and over conducted in 1976 by researchers at the University of Michigan, but never before analyzed from this theoretical perspective. In addition to parental and current background data, this survey focuses on a wide range of personal and social adjustment domains: Feelings and sources of well-being (or depression); self-perceptions; achievement and affiliation needs; values and experiences in marriage; values and experiences in parenthood; orientations and experiences in work; and symptom patterns (including anxiety). Information on these domains is represented by 147 major questions, most of which contain multiple sub-items. Exploratory and confirmatory factor analyses by the original investigators have already identified numerous scales of relevance to the P.I.'s research, and the data allow for extensive additional scaling. The proposed research expands upon the P.I.'s previous work on the relation of number of siblings to cognitive ability among young people, and educational attainment among adults, The current proposal is concerned with whether there are adult social and personality adjustment differences associated with coming from families of different size when parental background is held constant. In addition, the research will use path analysis to understand the indirect and direct effects of family background and number of siblings as these operate through the respondent's educational attainment to affect social and personal adjustment. A major reason for this research is that the American people are just beginning to undergo a significant transition in the family size of children - a transition that has lagged by almost a century the revolution in the family size of women. Only with the "baby bust" are most children during the Depression was actually of three or fewer offspring. The family size of children during the Depression was actually slightly larger than during the baby boom. Therefore, it seems of some importance to examine objectively the effects of the beginning of childrearing in small families for the majority of American children.